The present invention relates to a process for preparing graft copolymers having a polyolefin main chain containing one or multiple polar or nonpolar side chains and the products obtained therefrom.
Graft copolymers combining a polyolefin main chain with at least one nonpolar polyethylene-like polymer side chain are useful as compatibilizers for e.g. polyolefin (e.g. iPP) and polyethylene blends. The preparation of actual polyolefin-polyethylene graft copolymers (e.g. iPP-g-PE) is a very tedious process.
Graft copolymers combining a polyolefin main chain with at least one type of polar polymer side chain may be used to enhance the properties of polyolefin polymers that have an inherent nonpolar character that leads to drawbacks for certain applications, because of poor adhesion, printability and compatibility that can restrict their efficacy. Furthermore, such graft copolymers are useful as compatibilizers for e.g. polyolefin (e.g. iPP) and polar polymers (e.g. polycarbonate) blends.
It is known that craft copolymers may be prepared using as a main chain a well-defined randomly functionalized polyolefin, containing functionalized short chain branches. This main chain polyolefin is prepared in a separate process to which the side chains are added using an additional catalyst in a subsequent process.
Other, related prior art (Becquart, Macromol. Mater. Eng. 2009, 294, 643-650) uses a process where poly(ethylene-co-vinyl alcohol) (EVOH) is applied as a poly(hydroxyl) functionalized polyethylene and treated with a polyester in the presence of SnOct2 as transesterification catalyst to form the corresponding EVOH-graft-polyester graft copolymers.
The formation of the polar or nonpolar polymer side chains can either be carried out by growing these polymer side chains from the reactive substituents on the polyolefin main chain (grafting from approach) or by attaching a pre-synthesized polymer to the reactive side groups of a polyolefin main chain (grafting onto approach).
The aim of the present invention is to provide an easy, versatile and tunable process for the preparation of graft copolymers.
It is moreover an aim of the present invention to produce graft copolymers having a polyolefin main chain and at least one type of polar or nonpolar (preferably polyethylene-like polyester) polymer side chains.
It is moreover an aim of the present invention to provide copolymers that can be used as compatibilizers for blends of polyolefins and polar polymers, such as iPP with polycarbonate, or for blends of polyolefins and nonpolar polymers, such as iPP with PE.
One or more of these aims are obtained by the process according to the present invention.